Process for the shaping of fiber building board

ABSTRACT

A PROCESS FOR THE SHAPING OF FIBER BOARD IN WHICH A HEATED CORE WITH A CURVED SURFACE IS FORCEABLY APPLIED AGAINST FIBER BOARD WHICH IS MOISTENED IN THE REGION OF CONTACT, THE BOARD BEING SUPPORTED ON A FLAT BED OF RESILIENT MATERIAL WHICH PERMITS INDENTATION OF THE CORE THEREIN AND DEFORMATION OF THE BOARD WHILE REMAINING IN CONTINUOUS CONTACT WITH THE BOARD.

Jan. 19, 1971 H. BRODERSEN EI'AL 3,557,277 I PROCESS FOR THE SH'APING OF FIBER BUILDING BOARD Original Filed Aug. 9, 1967 2 Sheets-Sheet 1 Jan. 19, 1971 BRQDERSEN ETAL 3,557,277

PROCESS FOR THE SHAPING OF FIBER BUILDING BOARD 2 Sheets-Sheet 2 Original Filed Aug. 9, 1967 FIG. 3

i ll] Patented Jan. 19, 1971 Int. Cl. B29 5/04 US. Cl. 264-316 8 Claims ABSTRACT OF THE DISCLOSURE A process for the shaping of fiber board in which a heated core with a curved surface is forceably applied against fiber board which is moistened in the region of contact, the board being supported on a fiat bed of resilient material which permits indentation of the core therein and deformation of the board while remaining in continuous contact with the board.

This is a continuation of application Ser. No. 659,502, filed Aug. 9, 1967, now abandoned.

BRIEF SUMMARY OF THE INVENTION The invention relates to a process for the shaping by deformation of fiber building board, and in particular to the shaping of hard fiber board at locally limited regions. The process is also suitable for the shaping of fiber board of other kinds, wherein the composition of the basic aggregate varies.

It is known to shape or deform fiber board with the aid of inflatable tubing or air cushions and mould walls against which the fiber boards are pressed by the tubing or air cushions. Furthermore, it is known to shape or deform fiber board by bending a fiber board retained on a core about the core with the aid of a mandrel or a roller. With this arrangement, it is also known to retain the fiber board in the zone of the stretched fibers by means of steel straps.

However, all these known processes have the disadvantage that in the case of shaping with small bending radii, surface cracks are formed on the surfaces of the fiber boards.

In accordance with the invention, there is provided a process wherein the fibers of the fiber board are retained in their original relative position during the shaping process and without utilizing supplementary means, whereby the surface structure of the fiber board is maintained, particularly on the stretched side of the fiber board. Thereby, the formation of surface cracks is avoided.

This is achieved by an arrangement wherein the fiber board is subjected to deformation pressure in the region or regions to be deformed, between a substantially plane abutment bed of resilient material on the bearing face for the fiber board and a heated core pressed into contact with the opposite face of the board, while the board remains continually in complete contact with the resilient material of the abutment bed and is pressed thereinto.

The resilient abutment bed may be made from a natural or synthetic rubber or from a synthetic resilient plastic material. The bed must have a degree of hardness between 20 and 70 Shore.

The particular value of hardness within the above range is selected in accordance with the degree of curvature of the deformation to be produced. For deformation of slight curvature, the hardness is less than that for deformation of considerable curvature. In the case of a deformation having a bend radius of 45 millimeters, an

abutment bed made of rubber and having a hardness of 40 Shore has been found to be advantageous. The thickness of the resilient abutment bed is preferably such that, after the necessar indentation upon the application of the required deformation pressure, the bed still exhibits a certain degree of resilient compressibility. It is the purpose of the resilient bed, in cooperation with the flexibility of the fiber board material achieved by moistening, to prevent the fibers of the fiber board from being displaced relative to each other during the deformation process and in this way to insure that the structure of the fiber board will be retained also on the stretched surface.

The duration of the influence of the deformation pressure, which depends on the temperature of the heated core and on the moisture contained in the surface of the fiber board, amounts to about 20 to 60 seconds. The magnitude of the deformation pressure depends on the hardness of the resilient abutment bed and the magnitude of the deformation to be produced, and also on the thickness of the fiber board.

With the process according to the invention, it becomes possible to effect locally restricted deformation of a fiber board, with an extremely small radius of curvature, without the surface structure of the fiber board being detrimentally influenced and without the formation of surface cracks. Thus for example, in the case of hard fiber board, it becomes possible to effect bending or embossing with a bending radius which is as little as about three times the thickness of the fiber board, i.e. for example in the case of fiber board which is 2.5 mm. thick, embossing or other deformation or shaping may be effected with a bending radius of approximately 8 mm., in the case of 3.2 mm. thick fiber board deformation having a bending radius of 10 mm. and in the case of 4 mm. thick hard fiber board deformation having a bending radius of substantially 15 mm., without detachment of fiber from the surface.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view partially in section of a first embodiment according to the invention;

FIG. 2 shows the device according to FIG. 1, during the exertion of the deformation pressure;

FIG. 3 is a sectional view of a second embodiment for producing locally embossed portions in a fiber board, taken along the line III-III in FIG. 4; and

FIG. 4 is a plan view of a fiber board formed with embossed portions or indentations according to FIG. 3.

DETAILED DESCRIPTION Referring to the drawing the device is seen to be constructed in the manner of a press and it includes an abutment member 2 made of a resilient material, for example rubber, arranged in a U-shaped support member 1, and also a rigid core 3 which is adapted to be heated by means of a heating device of any desired type and which in crosssection corresponds to the shape of the convex side of the deformation to be produced. The core 3 is adapted to be displaced towards and away from the bed 2. For this purpose, the core 3 is secured on a press ram or plunger 4 adapted to be extended from a cylinder 5 by the feeding of a pressure fluid into the cylinder. As shown in FIG. 2, a fiber board 6 is bent approximately at right angles, the core 3 being circular in cross-section and having a radius corresponding to the radius of the bent portion to be produced. The core 3 could also have a circular cross-section only in its lower portion and be given any other desired shape in its upper portion. Furthermore, depending on the bending radius of the deformation to be produced, the core 3 could have in its lower portion, or throughout, a smaller or larger curvature which could for example also be oval.

For producing the deformation, the fiber board 6 to be deformed is first sprayed by a spraying device (not shown), in the zone where the deformation is to be produced, with moist steam. Alternatively, it can be moistened in some other manner until a moisture discoloration indicates that the fiber board is sufiiciently moistened in the surface zone to provide the flexibility necessary for the process according to the invention. The duration of the spraying of the fiber board with steam may, depending On the nature and condition of the board, amount to between half a minute and one and a half minutes. If required, moistening may be effected also on both sides of the fiber board.

Thereafter, the moistened fiber board 1 is laid on the abutment bed 2 which is designed to have a planar upper surface, and the core is caused to contact the fiber board 6 by extending the ram 4. Alternately, the fiber board 6 may be introduced sidewards between the abutment bed 2 and the extended core 3. As the core is brought into contact with board 6, (or prior thereto) the core 3 is heated to a tempertaure which is only slightly below the carbonization temperature of the material of the fiber board. When employing such a temperature, the fiber board is rapidly heated to its full depth at the point of contact with the core wtihout any danger of damage due to the effect of heat, and the moisture is rapidly withdrawn from the fiber board. Thus, the press ram 4 is again extended with the heated core 3 to apply deformation pressure to the Zone of the fiber board 6 beneath the heated core. The core is pressed into the abutment bed 2, with the fiber board interposed therebetween, until the fiber board 6 has been given the substantially rectangular bend as shown in FIG. 2. The deformation pressure is maintained until it is seen that the moisture has been withdrawn from the board. Depending on the heating temperature of the core 3, which is between 100 C. and 240 C., the duration of application of the deformation pressure is between 20 and 60 seconds. After this, the fiber board exhibits an adequate degree of dimensional stability at the point of deformation and may be removed from the press. During the deformation, the resilient material of the abutment bed 2 bears closely against the bent portion of the board and in this way prevents the formation of cracks on the stretched side of the bent portion of the board, inasmuch as the fibers of the fiber board are retained in position.

FIG. 3 shows a similar device which operates, however, for producing local deformations in the form of embossed portions, for example, intersecting reinforcement or decoration beads 7 (FIG. 4). For this purpose, the core 13 is in the form of a male die and is formed with intersecting, downwardly-projecting ribs 14. In order that the fiber board 6 will not undergo any surface bending, during the shaping process, between the beads 7, the press is provided with pressure member 15 (FIG. 3) which hold the fiber board down in the zone surrounding the beads to be produced, to maintain the planar form of the board between the ribs.

The abutment bed 2, which is made of a resilient material, is, to correspond to the length of the bead 7, designed to be wider than in the case of the embodiment according to FIG. 1, but it is again arranged in a support member 1 of U-shaped cross-section. Again, the core 13 is secured to the press ram 4 of the cylinder on which also 4 the pressure members 15 for holding down the fiber board 6 may be attached.

The deformation is effected in the same manner as described with respect to FIGS. 1 and 2.

In the case of both embodiments, the core 3 or 13 is hollow and is adapted to be heated by introducing, a liquid serving as a heat carrier via a stub pipe 16.

What is claimed is:

1. A process for the permanent shaping of wood fiber hard board by deformation in a locally limited region, said process comprising moistening the board in the region to be deformed to such an extent that a visible moistening discoloration is produced in said region on the board surface, heating the moistened region which is to be deformed, and pressing the moistened region of the board, during the heating, into an abutment bed of resilient material with a hardness of 2070 Shore and formed with a depth greatly exceeding the thickness of the board to deform the board with a small radius of curvature, the moistened region of the board being pressed into the resilient material of the bed to a depth such that the resilient material through lateral and upward expansion during the pressing maintains full and constant contact with the entire region of deformation of the board, and continuing the pressing of the board until the moisture previously incorporated in said region has been substantially evaporated whereupon the board assumes a permanent deformed shape and then terminating the pressing of the board and removing the thus permanently deformed board from the bed.

2. A process as claimed in claim 1, wherein said moistening is effected by spraying the board with moist steam.

3. A process as claimed in claim 1, wherein said moistening is effected on both sides of the board.

4. A process as claimed in claim 1, wherein said moistening of the board is effected in a period of time of between about 30 and seconds.

5. A process as claimed in claim 1, wherein the board is heated to a temperature slightly below the carbonization temperature of the fiber board.

6. A process as claimed in claim 1, wherein said deformation is local and constitutes an embossment, said fiber board being maintained in an original undeformed state outside the region in which the board is deformed.

7. A process as claimed in claim 1, wherein said force is applied for a duration of about 20 to 60 seconds.

8. A process as claimed in claim 1 wherein said contact of the bed with the moistened board during the pressing operation causes the board to be smooth and continuous in the region of the deformation while the fibres of the board remain intact throughout the thickness of the board.

References Cited UNITED STATES PATENTS 2,120,328 6/1938 Ferngren 18-56 2,581,222 1/1952 Varner 264339X 2,803,188 8/1957 Duvall 264-293X 3,274,047 9/ 1966 Sloan 264-320X 3,447,199 6/ 1969 Trimble 264-320X ROBERT F. WHITE, Primary Examiner R. R. KUCIA, Assistant Examiner U.S. C1. X.R 264322, 339 

